base (version 3.2.1)

sets: Set Operations


Performs set union, intersection, (asymmetric!) difference, equality and membership on two vectors.


union(x, y) intersect(x, y) setdiff(x, y) setequal(x, y)
is.element(el, set)


x, y, el, set
vectors (of the same mode) containing a sequence of items (conceptually) with no duplicated values.


A vector of the same mode as x or y for setdiff and intersect, respectively, and of a common mode for union.A logical scalar for setequal and a logical of the same length as x for is.element.


Each of union, intersect, setdiff and setequal will discard any duplicated values in the arguments, and they apply as.vector to their arguments (and so in particular coerce factors to character vectors).

is.element(x, y) is identical to x %in% y.

See Also


plotmath’ for the use of union and intersect in plot annotation.


Run this code
(x <- c(sort(sample(1:20, 9)), NA))
(y <- c(sort(sample(3:23, 7)), NA))
union(x, y)
intersect(x, y)
setdiff(x, y)
setdiff(y, x)
setequal(x, y)

## True for all possible x & y :
setequal( union(x, y),
          c(setdiff(x, y), intersect(x, y), setdiff(y, x)))

is.element(x, y) # length 10
is.element(y, x) # length  8

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